The present invention relates to thin film devices, typified by semiconductor devices and TFTs (thin film transistors) for use in liquid crystal displays, and to a method for manufacturing the thin film devices. Also, the present invention relates to a magnetic head, as well as a method for manufacturing the magnetic head, to be used for magnetic recorders such as hard disk drives (hereinafter, referred to as HDDs), as a more concrete example of the thin film devices.
In recent years, semiconductor devices have been advancing toward higher integration, while liquid crystal displays have been advancing toward larger size. Further, thin film devices other than these devices, such as SAW devices and micromachines, have been developed into practical use.
A thin film device and a method for manufacturing a thin film device according to the prior art are described below.
In particular, the following description is centered on the pattern forming method using a dry etching process of electrical wiring for a thin film device.
FIGS. 9A and 9B show a pattern forming process of a conductor layer serving for electrical wiring using the dry etching process in conventional semiconductor devices. The method of forming a conductor layer pattern using the conventional dry etching process is described below.
In FIGS. 9A and 9B, in which FIG. 9A shows cross-sectional structure of the film before the dry etching and FIG. 9B shows that after the dry etching, reference numeral 41 denotes a Si substrate, 42 denotes a gate insulating film formed of a 4 nm thick SiO2 film, 43 denotes a gate electrode made of tungsten (W) having a film thickness of 150 nm and forming a conductor layer serving as an electrical wiring, and 44 denotes an etching mask for the gate electrode 43 made of SiN. Numeral 43a denotes a gate electrode wiring formed by patterning the gate electrode 43 by dry etching.
Now the gate electrode pattern forming process using the dry etching process in conventional semiconductor devices is explained.
First, a Si substrate fabricated up to the etching mask 44 is set in a reaction chamber of a dry etching apparatus. Next, plasma of Cl2 and O2 mixed gas is generated, the gate electrode 43 is etched on the basis of the etching mask 44, and then the etching mask 44 is removed, by which a pattern of the gate electrode 43 is obtained.
However, in this conventional method, during the dry etching process of the gate electrode 43 made of tungsten, the etching selection ratio with SiO2, which is the thin gate insulating film 42 as a ground, is as poor as around 10, and moreover the processing must be done with an enlarged over etching on account of the micro-loading effect that a difference in etching rate occurs between a micro-pattern region and thick pattern region. As a result, as shown in FIG. 9B, there occur regions where the ground SiO2 gate insulating film 42 disappears so that good device characteristics could not be obtained. Also, in the future, as the gate insulating film becomes thinner and thinner with the progress toward higher integration, conventional methods would become insufficient.
Accordingly, an object of the present invention is to provide a thin film device, as well as a method for manufacturing the thin film device, which allows a conductor layer serving as an electrical wiring to be formed at high selection ratio with respect to a ground layer by using a dry etching process.
In order to achieve the above object, the present invention has the following constitutions.
According to a first aspect of the present invention, there is provided a thin film device in which a conductor layer serving as an electrical wiring in the thin film device is a conductor layer that can be dry-etched by an oxygen-containing gas.
According to a second aspect of the present invention, there is provided a thin film device in which a conductor layer serving as an electrical wiring in the thin film device is formed of two or more conductor layers, and a conductor layer on one side close to a substrate, out of the two or more conductor layers, is a conductor layer that can be dry-etched by an oxygen-containing gas.
According to a third aspect of the present invention, there is provided a thin film device according to the first aspect, wherein the conductor layer that can be dry-etched by the oxygen-containing gas is made of Ru or RuO2.
According to a fourth aspect of the present invention, there is provided a thin film device according to the second aspect, wherein an upper layer of the two or more conductor layers contains any one of polysilicon, W, WN, Cu, Al, Ag, and Au.
According to a fifth aspect of the present invention, there is provided a thin film device according to the first aspect, wherein the thin film device is a semiconductor device or a TFT for liquid crystal display.
According to a sixth aspect of the present invention, there is provided a method for manufacturing a thin film device, comprising:
depositing on a substrate a conductor layer which is etchable by an oxygen-containing gas and which serves as an electrical wiring;
forming an etching mask pattern on the conductor layer; and
thereafter, performing dry etching of the conductor layer with plasma of a gas containing at least oxygen to thereby accomplish a patterning of the conductor layer.
According to a seventh aspect of the present invention, there is provided a method for manufacturing a thin film device, comprising:
depositing on a substrate a lower conductor layer which is etchable by an oxygen-containing gas and which serves as an electrical wiring, and depositing one or more upper conductor layers on the lower conductor layer;
forming an etching mask pattern on the conductor layers; and
thereafter, preforming dry etching of the conductor layers with plasma of a gas containing at least oxygen to thereby accomplish a patterning of the conductor layers.
According to an eighth aspect of the present invention, there is provided a method for manufacturing a thin film device according to the seventh aspect, wherein the dry etching of the upper conductor layer is performed with plasma of a halogen-containing gas.
According to a ninth aspect of the present invention, there is provided a method for manufacturing a thin film device according to the sixth aspect, wherein the conductor layer that is etchable by the oxygen-containing gas is made of Ru or RuO2.
According to a 10th aspect of the present invention, there is provided a method for manufacturing a thin film device according to the seventh aspect, wherein the upper conductor layer contains any one of polysilicon, W, WN, Cu, Al, Ag, and Au.
According to an 11th aspect of the present invention, there is provided a method for manufacturing a thin film device according to the sixth aspect, wherein the thin film device is a semiconductor device or a TFT for liquid crystal display.
According to a 12th aspect of the present invention, there is provided a thin film device as defined in the first aspect, wherein the thin film device is a magnetic head in which the conductor layer serving as the electrical wiring and being dry-etchable by the oxygen-containing gas is a non-magnetic conductor layer electrically connected to a magneto resistive element.
According to a 13th aspect of the present invention, there is provided a thin film device as defined in the first aspect, wherein the thin film device is a magnetic head in which the conductor layer serving as the electrical wiring and being dry-etchable by the oxygen-containing gas is a conductor layer electrically connected to a magnetoresistive element and the conductor layer is made of Ru or RuO2.
According to a 14th aspect of the present invention, there is provided a thin film device according to the 13th aspect, wherein the conductor layer is a pair of lead electrodes electrically connected to the magnetoresistive element of the magnetic head.
According to a 15th aspect of the present invention, there is provided a thin film device according to the 13th aspect, wherein the conductor layer is a pair of lead electrodes electrically connected to the magnetoresistive element of the magnetic head, and wherein each of the lead electrodes is comprised of two or more conductor layers and material of a conductor layer on one side in contact with the magnetoresistive element, out of the two or more conductor layers, is Ru or RuO2.
According to a 16th aspect of the present invention, there is provided a thin film device according to the 13th aspect, wherein Ru or RuO2 as a contact layer is sandwiched between the magnetoresistive element of the magnetic head and a pair of lead electrodes electrically connected to the magnetoresistive element,
According to at 17th aspect of the present invention, there is provided a thin film device comprising:
an insulating ground layer;
a lower shield magnetic layer formed on the insulating ground layer, a magnetoresistive element selectively formed on a first insulating layer formed on the lower shield magnetic layer;
a permanent magnetic domain control layer formed with the magnetoresistive element interposed therein in order to give a magnetic bias to the magnetoresistive element layer;
a pair of lead electrodes formed with a specified spacing from each other and provided to sense variations in electrical resistance of the magnetoresistive element due to external magnetic fields;
a second insulating layer formed so as to cover the magnetoresistive element, the permanent magnetic domain control layer, and the pair of lead electrodes; and
an upper shield magnetic layer formed on the second insulating layer, wherein
Ru or RuO2 is used as the pair of lead electrodes connected to the magnetoresistive element, or as a contact layer of the lead electrodes.
According to an 18th aspect of the present invention, there is provided a thin film device according to the 17th aspect, wherein the first insulating layer is a lower gap layer and the second insulating layer is an upper gap layer.
According to a 19th aspect of the present invention, there is provided a method for manufacturing a thin film device including a process for patterning a pair of lead electrodes on a magnetoresistive element portion and on a permanent magnetic domain control layer formed at both end portions of the magnetoresistive element in a direction of track width on a lower shield layer and a first gap film both formed on a substrate, with the lead electrodes to be electrically connected in series to the magnetoresistive element, wherein the process of patterning the lead electrodes comprises:
depositing a film of Ru or RuO2 serving as the lead electrodes;
forming an etching mask pattern on the lead electrodes; and
thereafter performing a dry etching process of Ru with plasma of a gas containing at least oxygen.
According to a 20th aspect of the present invention, there is provided a method for manufacturing a thin film device according to the 19th aspect, further comprising:
forming the etching mask pattern by depositing a film of SiO2 or SiN;
thereafter forming a resist pattern on the etching mask pattern by photolithography; and
thereafter forming the SiO2 film or SiN film by dry etching.
According to a 21st aspect of the present invention, there is provided a method for manufacturing a thin film device according to the 20th aspect, wherein the SiO2 film or SiN film of the etching mask is used as part of an insulating film on the lead electrodes.
According to a 22nd aspect of the present invention, there is provided a method for manufacturing a thin film device including a process for patterning a pair of lead electrodes on a magnetoresistive element portion and on a permanent magnetic domain control layer formed at both end portions ofthe magnetoresistive element in a direction of track width on a lower shield layer and a first gap film both formed on a substrate, with the lead electrodes to be electrically connected in series to the magnetoresistive element, wherein the process of patterning the lead electrodes comprises:
forming the lead electrodes from two or more conductor layers, a material of the conductor layers in contact with the magnetoresistive element being Ru or RuO2;
forming an etching mask pattern on the conductor layers;
thereafter performing a dry etching process of the lead electrode upper layer other than the Ru or RuO2 layer with plasma of a gas containing halogen; and
thereafter performing a dry etching process of the Ru or RuO2 layer with plasma of a gas containing at least oxygen.
According to a 23rd aspect of the present invention, there is provided a method for manufacturing a thin film device including a process for pat terning a pair of lead electrodes on a magnetoresistive element portion and on a permanent magnetic domain control layer formed at both end portions of the magnetoresistive element in a direction of track width on a lower shield layer and a first gap film both formed on a substrate, with the lead electrodes to be electrically connected in series to the magnetoresistive element, wherein the process of patterning the lead electrodes comprises:
forming a Ru layer on one side of the magnetoresistive element closer to the lead electrodes;
performing a patterning of the magnetoresistive element and a patterning of the permanent magnetic domain control layer on both end portions of the magnetoresistive element in the track width direction;
thereafter depositing a film of the lead electrodes and forming an etching mask on the film of the lead electrodes by photolithography;
thereafter performing a dry etching process of the film of the lead electrodes with plasma of a halogen-containing gas; and
thereafter performing a dry etching process of the Ru layer with plasma of a gas containing at least oxygen.
According to a 24th aspect of the present invention, there is provided a method for manufacturing a thin film device including a process for patterning a pair of lead electrodes onto a magnetoresistive element portion and on a permanent magnetic domain control layer formed at both end portions of the magnetoresistive element in a direction of track width on a lower shield layer formed on a substrate, with the lead electrodes to be electrically connected in series to the magnetoresistive element, wherein the process of patterning the lead electrodes comprises:
forming a RuO2 layer on one side of the magnetoresistive element to be closer to the lead electrodes;
performing a patterning of the magnetoresistive element and a patterning of the permanent magnetic domain control layer on both end portions of the magnetoresistive element in the track width direction;
thereafter depositing a film of the lead electrodes and forming an etching mask on the film of the lead electrodes by photolithography;
thereafter performing a dry etching process of the film of the lead electrodes with plasma of a halogen-containing gas; and
thereafter performing a dry etching process of the RuO2 layer with plasma of a gas containing at least oxygen.
According to a 25th aspect of the present invention, there is provided a thin film device according to the 16th aspect, wherein a material of the lead electrodes other than the Ru or RuO2 is a non-magnetic metal such as W, Ta, Rh, Cr, Al, or Ir, or an alloy containing any of these elements.
According to a 26th aspect of the present invention, there is provided a method for manufacturing a thin film device according to the 14th aspect, wherein a material of the lead electrodes other than the Ru or RuO2 is a non-magnetic metal such as W, Ta, Rh, Cr, Al, or Ir, or an alloy containing any of these elements.